Due to the advances in electronics technology, there is an ever increasing need for miniaturized components and assemblies. This results in a need to fabricate printed circuit boards which are smaller than ever before required. Electrical connectors for connecting circuit boards to other circuit boards in such devices are required to be accordingly smaller. One example of such an electrical connector is a daughter board connector which is typically disposed on the edge of a printed circuit board and mates with a complimentary motherboard connector in a right angle orientation. The daughter board may contain a plurality of these electrical connectors along its mating edge. There is typically a large number of very tightly spaced connections that are required to be made between the daughter board and the mother board through the electrical connectors.
As the sizes of the boards and connectors are reduced, the precision required in order to properly align the mating connectors is greatly increased. If precise alignment is not achieved, a condition known as stubbing occurs between the contacts of the electrical connectors. Stubbing can occur as a result of misalignment between contacts within an electrical connector. While the housings of each daughter board connector and mother board connector may be perfectly aligned, the associated electrical contacts mounted therein may be out of alignment with each other and will jam against their respective complimentary contacts upon mating. Since the contacts are very small, they are delicate and subject to breaking when stubbing occurs. A problem therefore exists in that as electrical connectors are required to be smaller and more densely populated with contacts, precision alignment between mating contacts is difficult to achieve. This problem is exaggerated by the fact that an overmolded contact will unavoidably contain excess flashing as a result of the seams in the mold.
The cavity into which this overmolded contact must be placed has a diameter which is large enough to accept the overmolded contact with the additional flashing on its periphery. Because it is necessary to allow for this additional space, there will be some play between the overmolded contact and its associated housing cavity. A small degree of play between the housing cavity and the overmolded contact will result in a deflection of the contact at the mating end which extends from the housing. For example, a very small amount of flashing appearing on the edge surface of an overmolded contact will result in a deflection at the tip of the contact. This deflection is not acceptable and will result in stubbing problems in high density connector.
While flashing is not typically a problem in larger parts because it is a small percentage of the overall surface area of the part, as the surface area of the part becomes smaller the flashing becomes a larger percentage of that surface area thus contributing greater to any misalignment thereof. The flashing therefore creates a problem in that it requires the associated cavity to be larger than necessary in order to achieve precise alignment between the electrical contact and the housing.
An example of a known overmolded contact 102 is shown in FIGS. 1 & 2. Here the center contact 106 is overmolded and placed into an outer contact 104. If the center contact 106 is slightly out of position with respect to the outer contact 104, stubbing will occur upon mating with a complementary contact. The concentric relationship between the center contact 106 and the outer contact 104 is lost due to the play between the overmolded dielectric 108 and the outer contact 106. This problem can be addressed by trimming the flashing 110 from the dielectric 108 and reducing the cavity diameter of the outer contact 104 to achieve precise concentricity between the inner and outer contacts 106,104. Because of the size of the molded parts, approximately 1/16 in. in diameter, and small amount of flashing 110 that usually exists, about 0.002 to 0.004 in. high, the trimming process is expensive and not always effective. A deflection as indicated by ".theta." in FIG. 1 will result to cause a stubbing condition.